1. Field of the Invention
This invention relates to a control system for automated guided vehicles. In particular, it relates to an operation control system for a plurality of automated guided vehicles used in an unmanned conveying system.
2. Description of the Related Art
Automated guided vehicles are widely used for conveying articles in production lines, warehouses, etc. and these automated guided vehicles are equipped with driving and steering means and are able to automatically travel along a predetermined guide path.
A control system for controlling the operation of a plurality of these automated guided vehicles through guide wires installed along the travel path of the automated guide vehicles is widely used in unmanned conveying systems for production lines, such as a machine assembly line, instead of the conventional fixed type of conveying equipment such as belt or roller conveyors.
The unmanned conveying system has an advantage in that the automated guided vehicles can travel independently from one another, and is particularly suitable for application in production lines for the manufacture of many diverse items in small lots.
In an unmanned conveying system, the respective automated guided vehicles can be loaded with different kinds of work pieces, to convey them to respective areas in which the manufacturing process corresponding to the kind of workpiece is carried out. Also, the respective automated guided vehicles can be loaded with the workpieces and with the machine parts required for the assembly of those workpieces, i.e., the respective automated guided vehicles can convey all of the articles required for an assembly to the assembly area as one load.
Further, a series of manufacturing steps can be executed by transferring the workpieces between the automated guided vehicles running on the assembly lines of different manufacturing steps. Accordingly, by utilizing the advantage of an independent mobility of the automated guided vehicles, the unmanned conveying system can be effectively applied to production lines for the manufacture of many items each in small lots.
Nevertheless, in this many item, small lot type of manufacturing process, the type and kind of workpieces or machine parts carried by the respective automated guided vehicles must be correlated.
For example, if workpieces are transferred from one manufacturing line to another, the type of workpieces transferred from one automated guided vehicle must be the same as the type of machine parts or other workpieces already loaded on the automated guided vehicle to which the workpieces are transferred from the vehicle of the other manufacturing line. That is, if the types of workpieces and machine parts loaded on the vehicles of the different manufacturing lines are not correlated, the manufacture of the workpieces by transferring them from one manufacturing line to another cannot be effected.
An object of the present invention is to provide an operation control system for automated guided vehicles which can correlate the automated guided vehicles of different manufacturing lines so that workpieces can be transferred from an automated guided vehicle of one manufacturing line to another specific automated guided vehicle of another manufacturing line.
Also, when the unmanned conveying system is employed in a manufacturing line such as a machine assembly line, the automated guided vehicles must travel while maintaining a predetermined interval between the vehicles. This is particularly required when the automated guided vehicles pass through assembly stations, as the workpieces must be supplied at constant predetermined intervals in the assembly stations, in the same way as of a conventional fixed conveyor system, to facilitate the assembly work of operators at the assembly stations.
Accordingly, a further object of the present invention is to provide an operation control system for automated guided vehicles by which the vehicles can be travelled at specific parts of the travel path thereof while maintaining a predetermined distance between the vehicles.
Further, the automated guided vehicles used in the unmanned conveying system are usually equipped with battery systems as power sources for the drive motors and other control devices thereof. This means that, upon starting or terminating the functioning of the automated guided vehicles, the operators must switch on or off the power switches at each vehicle individually, and in a system which employs a number of these vehicles, this operation of the power switches is troublesome and time consuming.
Therefore, another object of the present invention is to provide an operation control system for automated guided vehicles which includes a control device by which the starting and terminating of the functioning of all of the automated guided vehicles can be carried out simultaneously by a remote control operation.